Radio tuning means



s. Y. WHITE RADIO TUNING MEANS '7 Sheets- Sheet 1 Original Filed Nov. 6,1942 JNVENTOR.

Ski/7e Y White BY fibgwv AT TORNE Ma 7, 1946. s. Y. WHITE 2,399,704

' RADIO TUNING MEANs Original Filed Nov. 6, 1942 7 Sheets-Sheet 2 ATTOEA/EYS y 1946- 5. Y. WHITE 2,399,704

RADIO TUNING MEANS Original Filed Nov. 6, 1942 7 SheetsShe et 3INVENTOR. Sid/76y k W/7/fe arfian/l, 6W4

AT TORNE Y5 1 y S.IY. WHITE 2,399,704

RADIO TUNING MEANS Original Filed Nov. 6, 1942 7 Sheets-Sheet 4 fig 7May I916? s1 Y. WHITE 2,399,704

' RAD IO TUNING MEANS Original Filed Nov. 6, 1942 'r Sheets-Sheet 5 a aa a h n 4y v I I h In a;

h: N k R23 R a Q m w INVENTOI} s/zzney )(Wh/fe AT TORNEYS May 7, 1946.5. Y. WHITE 2,399,704

RADIO TUNING MEANS Original Filed Nov. 6, 1942 7 Sheets-Sheet 6 INVE NTOR.

V Sidney White A T TORNEYS y 7, 1946. s. Y. WHITE 2,399,704

RADIO TUNING MEANS Original Filed-Nov. 6, 1942 '7 Sheets-Sheet 7INVENTOR. I Sidney X W/7/fe A T TORNEYS plication, referred to above.

Patented May 7, 1946 UNITED STATES PATENT OFFICE S. Johnson, Chicago,111.; Alex Thomson administrator of said Victor S. Johnson, deceasedOriginal application November 6, 1942, Serial No. 464,812. Divided andthis application June 2, 1944, Serial No. 538,347

'7 Claims.

This invention relates .to radio tuning means including a tuning orcontrol member, a drive member, and intermediate movement transmittingmeans.

It is an important object of the invention to provide in radio apparatusa tuning inductor having relatively movable elements comprising a coiland a cooperating inductance changing core, a panel, supporting means atthe rear ofthe panel to support one of the inductor elements at adistance behind the panel, drive means extending rearwardly from thepanel connecting to the other inductor element to adjust its posltionwith reference to the first, the material or materials composing saidsupporting means and drive means being such that changes in position ofany substantial amount of one inductor element with reference to theother element due to changes in temperature of the apparatus areprevented.

r A further object of the invention is to provide a radio tuning meansfor tuning a radio circuit over an extended range of frequencies whichineludes, in combination, frequency determining elements, a controlmember acting on one of said elements to tune the circuit, a camprovided with a plurality of steps arranged to advance the controlmember to a plurality of different positions within its range ofadjustment in response to the movement of the cam, and a fine pitchadjusting screw in engagement with the cam and arranged to move thecontrol member bysmall amounts from any position determined by the cam,within the range of adjustment of the adjusting screw.

It is a further object of the invention to provide, in combination, aradio chassis having a movable control member, resilient means arrangedto support the chassis with limited free-' dom of movement in alldirections including a rotatable member, a drive connection between therotatable member and said movable control member, and a control knobconnected to rotate the rotatable member.

Other objects and advantages will hereinafter appear.

'The present application is a division of my pending application SerialNo. 464,812, filed November 6, 1942, for Device for adjusting or tuningto close limits.

No claim is made herein to the details of structure of the cam per se,nor to itscombination broadly with a member operated by it. Claims ofthis character are included in my parent ap- Cir For a betterunderstanding of the invention, reference is made to the followingdescription taken in connection with the accompanying drawings, inwhich:

Fig. 1 afront view of a radio tuner embodying the invention;

Fi 2 is-a vertical sectional view of the tuner of Fig. l'taken on theline 2-2 thereof;

Fig. 3 is a view partly in section showing the driving connections tothe adjusting screw or" the tunerdisassembled;

Fig. 4 is a horizontal sectional View of the tuner of Fig. 1 "taken onthe line 44 thereof;

Fig. 5 is afront viewwith portions cut away showing the drive cam of thetuner;

'Fig. 6 is a vertical sectional view of the cam shown in Fig. 5 taken onthe line 6'--6 thereof;

Fig. 7 is a front view, showing on an enlarged scale, one of the camadjusting blocks and its retaining spring;

Figs. 8 and 9 show modified forms of cam adjusting blocks with theirretaining springs;

10 is a side view of the drive camof the tuner showing also the ends ofthe adjusting screw and. the tuner push rod;

Fig. 1-1 is a rear view of the cam shown in Fig. 10 also showing the endof the tuner push rod operated by the cam;

Fig. l2-is an enlarged fragmentary view partly in section showing theadjusting screw, 2. portion of the camand the cooperating end of thepush rod with the cam at an intermediate position "between two tunersetting positions thereof;

of the tuner push rod;

Fig. '16 is a vertical section on an enlarged scale taken onth'e linel-B-IB of Fig. 4 showing por- "tions of the driving connections to thetuner adjusting screw;

Fig. 17 isavertical section on an enlarged scale taken on-the li'ne li-l1 of Fig. 4 showing por- "tions' of the driving connections to thecam;

Fig. I8 is a vertical section ori an enlarged scale taken on the linel'8--|8 of'Fig. 4 showing the resilientsupporting means for the rear endof the tuner chassis; and

Fig. 19 is arear view of the continuous dial of .the tuner and itsassociated parts, with the dial adjusted to itsfizeroposition.

Referring to Figs. 1, 2 and 4, the invention is shown in connection witha radio tuner adapted the tuner comprises an oscillator tube H (see Fig.v

4) provided with a tunable tank circuit |2 comprising a coil |3 formedof silver ribbon and a condenser l4 of fixed capacity whose ends are 7connected across the ends of coil |3. Coil I3 is wound in a helicalgroove formed in a cylindrical tube |5 of ceramic material which isfused to and supported by a rectangular block l6 also of ceramicmaterial. The ends of coil l3 are soldered to a pair of silver blocks l!which are secured to the supporting block I 6 by the screws l8 whichalso serve as the terminals of the resonant circuit. The block I6 isclamped between the upper and lower walls |92|| of a generally U shapeddie casting 2| which extends from the rear wall 22 of a closed casing23. The side walls 24-25 (Fig. 4) of casing 23 are secured by anysuitable means (not shown) to the front wall 26 of chassis Ill. Thecircuit I2 is tuned by means of a cylindrical powdered iron core 21which is mounted on a push rod 28, the portion 29 of rod 28 on which thecore 21 is mounted being of insulation material, as shown. Push rod 28is guided in openings 30 and 3| provided, respectively, in the wall 22and the rear wall 32 of the die casting 2|, Push rod 28 is biasedforwardly with a force preferably of a pound or more, by mean of aspring 33 (Fig. 4) Whose rear end is connected to a plunger 34 slidablein a cylindrical bore 35 formed in the casting 2|, the plunger 34 havingreadily separable connection with the rear end of the rod 28 by a bar 36which is secured to the end of plunger 34 by a screw 31. The tension ofspring 33 may be regulated by means of a rod 38 to which the front endof the spring is connected, and which is clamped in position in the bore35 by a screw 39. To prevent rotation of push rod 28 during itslongitudinal adjustment, it i provided along one side thereof near itsfront end with a groove 40 (see Figs. 4 and 12) in which a ball 4| isseated, the ball being carried by a bushing 42 and biased inwardly by aspring 43. The

bushing 42 is secured to the rear wal122 of casin 23 by the screws 44and is provided with a bore 30a. which assists bore 30 in supporting andguiding the push rod 28 during its longitudinal adjustment.

Referring to Figs. 1, 4 and 10, the front end of push rod 28 engages afloating cam C which is mounted for both rotation and longitudinalmovement, the cam being rotated by a gear 45 which is driven by ameshing gear 46 the latter gear being driven by a tuning knob 41 throughconnections to be later described. Rotation of the cam C by the knob 41and gear 45 serves to rapidly tune the resonant circuit l2 in stepsthrough a large range of frequencies in a manner to be later described.The cam C is also adapted to be moved bodily in a rearward direction totune circuit l2 through a smaller range of frequencies by means of anadjusting screw 48 of fine pitch as, for example, '75 threads per inch.Screw 48 may be suitably made of Monel metal, and at its rear endrigidly has secured thereto a button 49 of tough steel such as OhioAirdy (see Fig. 12). Button 49 has a conical shaped intermediate portion50 and terminates in a tip 5| of reduced diameter, the rear end of tip5| being ground to have a smooth spherical curvature as indicated at 52,a suitable radius of such curvature being about 5 inches.

For a more detailed description of step cam C reference is made to Figs.5, 6 and '7 wherein it is shown as comprising a disc shaped cam member53 which is preferably formed as a die casting of aluminum alloy havinga composition of approximately 4% copper, 6% silicon and 90% aluminum.The rear face of cam disc 53 is provided with 24 steps of increasingthickness, a hardened steel ball 54 being secured in each step in amanner described in the above noted application. The balls are of thesame diameter and are all disposed at the same radius from the center ofcam disc 53, the bearing face of each ball being elevated exactly .010inch above that of the next adjacent ball. As the cam is rotated, theballs are arranged to come successively into engagement with spacedapart surfaces 55 formed on the end of push rod 28 (see Figs. 10 and12),

- a deeper horizontal slot 56 being formed between the surfaces 55 sothat the high point of the ball is clear of the push rod. Vertical cuts51 are made in the end of the push rod at each side of the surfaces 55,so that both of these surfaces are of the same length to permit of theirbeing conveniently lap finished simultaneously to a smooth finish, theradius of curvature of which is the same as that the balls 54. From theupper surface 55 the top of the push rod tapers gradually rearwardly asindicated at 58, Figs. 10, 12 and 15. By this construction the positionof the push rod at each setting of the cam is not determined by the highpoint of the ball, which tendsto wear away more rapidly than otherportions thereof, but by lower zones on the ball which have lineengagement with the curved, surfaces 55. The construction also operatessubstantially the same in either direction so that the amount of torquerequired to be applied to the tuning knob 41 (Fig. 4) is substantiallythe same whether the push rod 28 is to be stepped forwardly orrearwardly by the cam.

Cam disc 53 is mounted for rotation and longitudinal movement on ahorizontal spindle 59 whose rear end is secured in a bore 60 provided inthe vertical wall 22 (Fig. 6) the spindle being secured by having itsend riveted over, as indicated at 6|. A threaded screw 62 passes throughan opening 63 provided at the center of cam disc 53, the front end ofscrew 62 having an enlarged cylindrical head 64 which is provided with ashort shoulder 65 which engages the front face of gear 45. A member 66formed of resilient material as, for example, Phosphor bronze isdisposed between gear 45 and a forwardly extending shoulder 61 providedat the center of cam disc 53. The several parts comprising the cam aresecured together by a pin 68a and a nut 68 which is threaded on the rearend of screw 52. A plurality of radial slits 69 are formed in member 66which define a series of radially extending spring fingers 10, the outerend of each finger being provided with a short lug The front face ofeach spring finger near the outer end thereof is cut away to form atapered surface 12 which is deepest at th outer end of the finger, asindicated at 13, and merges with the front surface of the finger in thecurve 14 (Fig. 5).

Means is provided for adjusting the thickness of cam C at the region ofeach ball 54. For this purpose the front surface of cam disc 53 isprovided with a plurality of radially extending grooves 15 whose bottomwalls 16 are inclined at a small angle as, for example, 2 degrees withreference to a vertical plane through the front face of the cam disc,this angle being exaggerated in the drawings for the purpose of clarity.Disposed in each of the grooves I5 is a thin compensating block I1 whosefront surface is vertical and whose rear surface is tapered at aninclination of the order of 2 and is seated against the bottom wall I6of the groove I5. The rear surface of each block I1 is biased againstthe bottom wall 16 of its groove by means of one of the spring fingersI0, the lug II on which bears against the front surface of thecompensating block, as shown in Figs. 5 and 6. Each block 11 is alsoheld firmly in engagement with one side wall of its groove 15 by meansof a spring 18 which is disposed between the side of the compensatingblock and the other side Wall of the groove I5. The ends of spring 18engage the ends of the compensating block I! and in the form of theinvention shown in Figs. 5 and 7 the inner end 19 of the spring liesflat against the inner end of the compensating block while the outer end80 of the spring i in the shape of a hook, thereby providing an opening8| between the outer end of the block and the end of the spring for apurpose to be later described. Since a compensating block I7 is providedopposite each ball 54 it will be readily understood that as a block ismoved radially inward within its groove 15, due to the gradual slope ofthe bottom wall I6 of the groove, the distance between the ball 54 andthe front vertical surface 82 of the block will be gradually increased,the compensating blocks thus affording a means for readily regulatingthe thickness of the cam within close limits at the region of each ball.The spring fingers I0, together with the springs 18, provide means forretaining the compensating blocks in their adjusted positions, so

that they do not move within their grooves during operation of the radiodevice.

Modified forms of springs are shown in Figs. 8 and 9. In the form shownin Fig. 8 the outer end 80 of the spring terminates in a short flatportion 03 which rests against the outer end of the compensating blockTI so that if the block is pushed inwardly along its groove by means ofa tool applied to the outer end 80' of thespring, all the applied forcewill be transmitted to the outer end of the block "I? and none of ittransmitted to the bowed portion of the spring. Such force applied tothe bowed portion might set up a strain therein which would remain afterthe adjustment of the block and possibl cause the block to creepslightly along its groove 15 for a short distance upon the operation ofthe device. Such creeping of the compensating block would change thethickness of the cam slightly at this region and introduce a slighterror in the setting of the push rod 28.

In the form of the invention shown in Fig. 9 the outer end of spring 18"is straight and bears against the outer end of compensating block 'I!"so that any radial pressure applied to the end 80 of the spring isentirely taken up by the compensating block, and none of it istransmitted to the bowed portion of the spring. Thus no strain is storedup in the bowed portion which might tend to cause the compensating blockto creep along its groove I slightly during the operation of the device.An opening 84 is provided in the outer end of the block TI" wherein theend of a tool may be inserted to pull the block outwardly along itsgroove in the cam disc 53 for a purpose to be later described.

For transmittin the rotation of knob 41 (see Figs. 4 and 17) to gearwheel48 and cam C, the gear 46 is secured to a shaft as by a pin 86, thefront end of shaft 85 being enlarged to form a disc 01 to the rearsurface of which a Bakelite gear wheel 88 is secured by screws 89. Theshaft 85 is journaled for rotation in a tubular bearing 90 which issecured to the front wall 26 and extends through an opening 9| providedin this wall. Gear wheel 88 is in turn driven by a Bakelite gear wheel92 which is secured to an enlarged central portion 93 of a hollowsupporting hub 94 as by screws 94. The hub 94 is journaled for rotationon a short spindle 95 whose rear end extends through an opening providedin the wall 20 and is threaded as at 96, to receive a lock nut 91 whichsecures the spindle 95 in position. At its front end the hub 94 isprovided with a pair of outwardly extending, radially disposed thin fins98 whose outer ends are seated in a pair of shallow grooves 99 formed ina rubber supporting collar I00. The collar I00 is in turn supported in arotatable metallic supporting cup IOI which is disposed in a circularopening I02 inthe front panel I03 of a closed casing I04 in which theradio chassis I0 is resiliently supported for a limited degree ofmovement in all directions. The cup IOI is provided with an outwardlyextending flange I05 which bears against the rear surface of the wallI03 and tuning knob 41 is provided with a threaded screw I00 forsecuringit to the cup I9I, the rearface of knob 4'! bearing against the frontsurface of panel I03, as shown in Fig. 4. Cup IOI near its front end isprovided with a reduced shoulder portion I 01 which bears against thefront surface of rubber collar I00 to take up the end thrust of suchcollar in a forward direction. Cup IN is shown as provided with fourfins I00 (see Fig. 17) which extend radially inwards into correspondinggrooves I09 provided in the rubber collar I00 so that rotation of thecup H is transmitted to the rubber supporting collar I00 and by thelatter through the fins 98 to the hub 94 and gear wheel 92. It will beobserved in Fig. 4 that there is a clearance space IIO provided betweenthe end of spindle 95 and the interior end wall III of the cup IOI.

From the above description it will be readily understood that the rubbercollar I00 not only serves as a portion of the means used to transmitthe rotation of tuning knob 41 to cam C, but also serves as a means forresiliently supporting a portion of the chassis I0 at its front end withlimited freedom of movement in all directions within the casing. I04.

The means for resiliently supporting the rear end of the chassis forlimited movement in all directions comprises a vertically disposednarrow plate IIZ (see Figs. 2 and 4) to the upper end of which issecured a short cylindrical stud II3 which is disposed in a centralopening I I4 formed in a rubber supporting collar II 5. The stud I I3has an enlarged flange portion I I6 whose rear surface bears against thefront surface of rubber collar H5 and transmits any rearward thrust ofthe chassis I0 to the center portion of the rubber collar. Such endthrust is taken up by a shoulder II.'I provided on a hollow supportingcup H8 in which the collar H5 is seated and which is secured in a fixedposition on the rear vertical wall H9 of easing I04 by a threaded screwI20.

For indicating the tuning of circuit I2 and the setting of core 21 asdetermined by the rotation of knob 41, gear 88 drives a Bakelite gearwheel I2I (see Figs. 1 and 4) to whose front face is secured by pins I22a thin metallic disc I23. Disc I23 carries near its outer periphery aBakelite ring I24 whose front face constitutes a graduated dial I25, thegraduations being discontinuous and shown as extending from 100 to 124megacycles, see Fig. 1. These graduations appear behind a glass I26 setin a window opening I2'I provided in front panel I03, a suitable indexmark I28 being provided on panel I03. At their centers gear wheel I2Iand disc I23 are secured to a hub I29 which is mounted for free rotationon the peripheral surface of the rear end portion of a hollow outboardbearing member I3I. Bearing member BI is secured in fixed position onthe chassis wall 26 by a retaining collar I32 which extends inwardly andoverlies an outwardly projecting flange I33 formed at the rear end ofmember I3I. Collar I32 is secured in position on wall 26 by any suitablemeans, as by the screws I34. The rotation of the cam C and the dial Iare limited to less than one revolution by two stops I on the gear l2Iwhich engage with a pin I30a fixed on the plate 26.

Referring to Figs. 4, l2 and 13, adjusting screw 48 is supported forrotation in a hollow supporting nut I35 which is provided with anoutwardly 0 extending flange I36 through which pass securing screws I31which secure the nut to the vertical wall 26. Throughout its centerportion nut I35 is cut awa as indicated at I38, to provide a clearancespace between the center portion of adjusting screw 48 and the centerportion of the nut. The front and rear end portions I39 and I40 of thenut are interiorly threaded to receive the screw 48 and at the bottomeach of the end portions I39--I40 is cut vertically as indicated at I4I,Fig. 13, and is also cut vertically in a direction normal to the axis ofscrew 48 at a distance from the end of the nut as indicated at I42, Twothreaded loading fingers I43 and I44 are thus formed which may be forcedslightly inwardly to load the screw 48 and eliminate the major portionof the backlash between the screw and nut. Each end portion I39 and I40of the nut has its outer surface cut away to receive a pair of clampingcollars slightly elliptical in shape before being placed in position onthe nut portions I39 and I40, the eccentricity of the members I45--I46being shown on an exaggerated scale in Fig. 14 in which the dot and dashline represents a circle. clamp member I45 and I46 is provided with apair of shallow bores I41 adapted to receive the end of a spanner wrenchused for rotating the clamp to bias its loading finger I43-I44 into firmengagement with the threads of screw 48. It will also be understood thatany Wear of the threads of screw 48 resulting from the continued use ofthe device may be taken up by slightly rotating the clamping collars I45and I46 on the nut. The illustrated means for supporting the adjustingscrew by nut portions which engage the threads of the screw at spacedapart regions thereof provides against any sidewise, vertical or endwiseundesired motion of the screw in the nut so that only the desiredlongitudinal movement of the screw due to its rotation is secured.

Screw 48 is rotated by means of a short shaft I48 whose rear end extendsinto a bore I49 provided in the screw and is a drive lit in the bore(see Figs. 4 and 12). Shaft I48 is firmly sup- I45I46 which are Each 5(see Fig. l).

ported for rotation in a forwardly projecting hub I50 formed on theoutboard bearing member I3I and which is connected thereto b a radialflange I-5I. The front end of shaft I48 (see Figs. 3 and. 4) is threadedas at I52, and is provided with a thin longitudinally extending slotI53, a nut I54 being screwed on to the threaded end portion thereof. NutI54 engages the front end of a thin flat key I55 whose inner end I56becomes seated against the rear wall I51 of the slot I53. The outer endsI'5'I of the key are disposed in a narrow slot I58 formed in the frontend of a rotatable hollow cup member I59 which is supported for rotationon the supporting hub I50, Cup I59 has secured to its outer periphery athin circular disc I60 whose front surface constitutes a graduated dialI6I whose graduations are continuous and disposed closely adjacent tothose of the dial I25 and appear through a circumferentially extendingportion I62 of the window opening I21 An index mark I63 is formed on thepanel I03 adjacent to the graduations of dial I6I. The hollow cup I59 isrotated by means of a rubber supporting collar I64 which is providedwith a pair of holes I65 into which extend a pair of forwardlyprojecting pins I66 which are carried by the cup I59. The front end I61of cup I59 is reduced in diameter to provide a shoulder I68 whichengages the rear face of rubber collar I64, as shown in Fig. 4. Rubbercollar I64 is seated in a hollow retaining cup I69 which is rotatable ina bore I10 provided in the front panel I03, the cup I69 having at itsend an outwardly turned flange Ill which engages the rear face of thepanel. The cup I69 is in turn rotated by a tuning knob I12 which issecured to the cup by a set screw I'I3, the rear face N4 of the knob I12being disposed against the front surface of the vertical panel I93, asshown in Fig. 4.

The front face of rubber collar I64 near its periphery bears against ashoulder II-5 provided on the retaining cup I69. The rubber supportingcollars I00 and I64 thus provide means for resiliently supporting thefront portion of the radio chassis I0 at spaced apart regions thereofwith limited freedom of movement in all directions within the casing I04while the rubber collar II5 similarly supports the rear portion of thechassis. Any forward movement of the chassis which might result fromshocks or vibrations imparted thereto is limited by the rubber collarsI00 and I64 which absorb the shock and transmit it to the panel I03, theportion of collar I64 within the shoulder I on cup I69 bulging forwardslightly, a suitable clearance space II6 being provided beyond the frontend of adjusting screw shaft I48 for this purpose. The portion of rubbercollar I00 disposed inwardly of the shoulder IN on cup IOI similarlybulges forward a slight amount. Any rearward movement of the chassisresulting from shock or vibration is limited and absorbed by the rubbercollar H5, the portion thereof which is disposed inwardly of theshoulder I I! on supporting cup I I8 bulging rearwardly a slight amount,a suitable clearance space I 11 being provided at the rear of collar II5for this purpose. Any vertical or sidewise movement of the chassis I0resulting from shock or vibration is transmitted to and absorbed by allthree of the rubber collars I00, I I5 and I64,

The rotation of adjusting screw 48 and continuous dial I6I is limited tosubstantially threefourths of a revolution by means of a pin I18 (Figs.4 and 19) which is set in the flange I5I and projects forwardly into ashallow circular groove I19 provided in the rear face of cup I59. A pairofspaced apart pin I80, I 8| (Fig. 19) are set in a the rear face of cupI59 and extend rearwardly into the groove I19 where one or the other ofthem comes into engagement with thepin I18 as the tuning knob I12 isrotated to its extreme position in one direction or the other. A thinwasher I82 (Fig. 4) is interposed between the dial disc I60 and theflange I5I to separate the dial disc I60 slightly from dial disc I23 sothat the two dials do not rub together.

Referring to Figs. 1 and 2, the ceramic block I6 is shown as alsosupporting a compressed powdered iron block I83 shown as having anarouate upper face I84. The block I83 is adjustably secured in positionon supporting block 15 bydevice is designed to prevent any change inposi- 1 tion of substantial amount of the iron core 21 with reference toits coil I3 due'to'changes in temperature of the apparatus. Thiscompensation is secured not by making the apparatus of relativelnon-expanding material such as Invar, but by assuring that the partswhich determine the distance between core 21 and coil I3 and the frontwall 26 expand and contract together by equal amounts so that therelative position of the core and coil remains unchanged.

In using the radio tuner the dial I25 is set at 124 and the dial I BI isset at 1000. The coil I3 is now adjusted lengthwise of push rod 28 byslightly spreading apart the upper and lower walls I9 and 20 of the diecasting 2I, see Figs. 1, 2 and 4, a special expanding tool (not shown)bein provided for this purpose, whereupon the coil supporting block I6is slid along the Walls I9 and 20 until the oscillator circuit I2 istuned to exactly 125 megacycles, as indicated by the sum of the readingson the dials I 25 and IBI. The expanding tool is then removed, whereuponthe supporting block I6 becomes firmly clamped in position by the wallsof casting 2|, it being found that this clamping action is adequate toprevent the supporting block from moving thereafter even when the radiotuner is subjected to sudden shocks or considerable vibration. The core21 is now in its extreme forward position with reference to coil l3, camdisc 53 is in the position shown in Figs. 5, 6, 10 and 11, and thebearing surfaces 55.0n the end of push rod 28 are in engagement with thelowest ball 54, as shown in Fig. 10. Knobs 41 and l12 are now rotated ina clockwise direction until dial I25 reads 100 land dial I 6| readszero, which adjustment moves the push rod 28 and core 21 to theirextreme rearward position. The iron block I83, see Figs. 1 and 2, isthen raised or lowered until the oscillator circuit I 2 is tuned to 100megacycles, whereupon the block is secured in fixed position bytightening the screws I85. The adjustment of this block has the eifectof chan ing the slope of the tuning curve of resonant circuit I2. Aftersuch adjustment of the circuit to the indicated frequencies, rotation ofknob I12 and adjusting screws 48 counterclockwise,- as indicated by thearrow in Fig. 1, for a distance of one division on continuous dial IBIpermits the cam C and push rod 28 to be moved forwardly a distance .0001inch, thereby tuning the circuit I2 to a frequency of 100,010 kc. asdetermined by taking the sum of the readings on dials I25 and I6I. Theknob I12 is now rotated another dial .division of dial I6I which causespush rod 28'and core 2'! to be moved forwardly anotherp0001 inch underthe bias of spring 33 and oscillator circuit I2 to be tuned to thefrequency 013100020 kc., as determined by adding together the two dialreadings'. When the knob I12 has thus been rotated through 100 dialdivisions of dial I6I, the circuit I2 will be tuned to 101 megacyclesand the iron core 21 will have been adjusted .010 inch forwardly of itsinitial position. By now rotating the knob I12 and dial IBI to theirinitial or zero positions, push rod 28 and core 21 will be movedrearwardly by screw 48 to their initial position, and the frequency ofoscillator circuit I2 will again be 100 megacycles. By now rotating knob41 counterclockwise, as indicated by the arrow in Fig. '1, until theouter dial I25 reads 101 megacycles, the cam disc 53 is rotated untilthe next lower ball 54 thereon comes into engagement with the bearingsurfaces 55 of push rod 28. Under the bia of spring 33, the push rod ismoved forwardly a distance of .010' inch and causes the circuit I2 to betuned to the indicated dial reading of 101 megacycles. Any slightinaccuracy of the tuning to this frequencymay be compensated for by theoperator withdrawing a screw 181 from a threaded opening 188 provided inthe cam casing 23, see Figs. 2 and 4. A special micrometer head (notshown) provided for this purpose is now inserted in the opening I88, theend of the micrometer screw engaging the end of spring 10, Fig. 7, andby rotating the micrometer screw the compensating block 11 which is inengagement with curved end 52, Fig. 12', of adjusting screw 40 is movedinwardly within its groove 15 to move cam disc 53 and push rod 28rearwardly a suitable amount until circuit I2 is tuned to the desiredfrequency. Should the compensating block be ad justed inwardly in itsgroove slightly too far, the micrometer head is withdrawn from theopening 188 and a tool inserted therethrou-ghfwhich has a projecting endportion which may be inserted within the opening 8|, Fig. 7, of spring18, then by pulling on the tool the compensatin block may be pulledoutwardly in its groove a substantial amount. After removing such tool,the micrometer head is again inserted in the opening I88 and thecompensating block 11 moved inwardly in its groove by the micrometerscrew until the correct resonant frequency of circuit I2 is secured.

The radio tuner may now be tuned consecutively through the next onehundred settings by rotating the knob I12 and dial IIiI consecutivelythrough one hundred divisions of this dial one by one until the dialreads 1000, when the circuit I2 will be tuned to 102 megacycles and pushrod 28 will be .020 inch forwardly of its initial position. By nowrotating knob I12 clockwise until continuous dial I6I reads zero andthen rotating the knob 41and dial I25 counterclockwise until a 43 in itsgroove by the micrometer device in the manner above described. Bycontinuing this operation repeatedly the circuit l2 may be tuned throughall the frequencies corresponding to the 2500 dial settings and thetuning of the circuit adjusted to the desired value for each of thedivisions on the outer dial I25 by adjusting the compensating blocks 1'!in their grooves in the manner above described. It will be understoodthat, after all the compensating blocks have been appropriatelyadjusted, the screw I81 will again be screwed into the threaded openingI88, Figs. 2 and 4, thereby sealing the cam C, adjusting screw 48 andtheir associated parts in the casing '23 against the entrance of dust ordirt particles which might otherwise collect on different parts of themechanism and destroy its accuracy by interfering with its properoperation. The radio tuner is then ready for operation, and it is foundthat within the short interval of four seconds the oscillator circuit l2may be readily tuned from any frequency to any of the other frequenciescorresponding to the 2500 different dial readings. If it is desired toadvance the push rod 28 rearwardly step by step by rotating the knob 41and cam C clockwise, when the rotation of the cam is commenced thetapered surface 12 on the front of spring finger 10 (Figs. 5, 10 and.12) immediately comes into engagement with the conical surface 58 ofbutton 49 and exerts a component of force on the spring finger and itsunderlying compensating block 11 which pushes the cam C rearwardly alongits supporting spindle 59 into the position shown in Fig. 12, so thatthe end of button 49 clears the edge of the next adjacent compensatingblock as this block is broughtinto position by the rotation of the cam.When the front face 82 of the next compensating block has been broughtopposite the curved surface 52 on the end of button 49, the taperedsurface 12 on its spring finger rides down the conical surface 50 as therotation of cam C continues and the cam moves forwardly under the biasof spring 33 (Fig. 4) until the spring finger is entirely clear ofbutton 49 and the front face 82 of the block is in engagement with thecurved surface 52 defining the end of button 49.

Referring to Fig. 9, the compensating block 11" is adjusted inwardlyalong its groove 15 in the cam by placing the end of the aforedescribedmicrometer screw in engagement with the fiat end 80 of its spring, andthen rotating the micrometer screw a suitable amount. Should thecompensating block accidentally be moved too far inwardly, it may bewithdrawn by placing the end of the aforementioned tool in the hole 84in the block and pulling the block outwardly in its groove, after whichthe block may be again moved inwardly by the micrometer screw to thecorrect position.

While the invention has been illustrated in connection with the tuningof an oscillator circuit, it will be understood that additional ironcores may be mounted on push rod 28 to tune the radio frequency circuitsof a radio receiver or other radio device, in the manner illustrated anddescribed in my aforementioned application. Furthermore, the push rod 28may be used to operate an adjustable gage used for measuring the size ofarticles as illustrated in my aforementioned application or foroperating the controlled element of any other device which is requiredto be adjusted within close limits.

While I have illustrated my invention as including a step cam as aspacing means for effecting different positions for the operated rod ormember 28, each of which cam steps as described differs uniformlyinthickness from the preceding one of said cam steps, it will beunderstood that for some purposes these cam portions 5 may have'anydesired different thicknesses 'to meet the requirements of differentpurposes of use, whether the limited amount of movement of the screw orcontinuously operated drive member 48 is equal to the difference betweensuccessive thicknesses of the cam or not. It will further be understoodthat my invention is adapted for use where lesser degrees of accuracy ofmovement are permissible than for the uses described. For example, forthe purpose of the relatively general grading or grouping of objects asto size, or the resonant selection of radio stations from a relativelysmall group of such stations such as the broadcast band, the high degreeof accuracy described may not be required. In such cases the spacingmeans or cam C need not be provided with the balls 54, but may be anintegral structure made from a single metal block with a degree ofaccuracy, in any case, that is commensurate with the intended purposesof the structure.

I have described what I believe to be the best embodiments of myinvention. I do not wish, however, to be confined to the embodimentsshown, but what I desire to cover by Letters Patent is set forth in theappended claims,

I claim:

1. Radio apparatus comprising, in combination, a tuning inductor havingrelatively movable elements comprising a coil and a cooperatinginductance-changing core, a panel, means at the rear of the panelarranged to sup port one of said inductor elements at a distance behindthe panel, drive means extending rearwardly from the panel connected tothe other inductor element to adjust its position with reference to saidone inductor element, the materials composing said supporting means anddrive means having coefficients of expansion such that changes inposition of any substantial amount of one inductor element withreference to the other element due to changes in temperature of theapparatus are prevented, and a control knob disposed in front of thepanel for actuating said drive means.

. 2. In combination, a supporting structure having an opening therein, aradio chassis having a movable control member, means arranged to supportthe chassis with limited freedom of movement in all directions includinga resilient rotatable member mounted in said opening and carried by saidsupporting structure, a drive connection between the rotatable memberand the said movable control member, and a control knob connected torotate said rotatable member, said drive connection including a shaftsupported on the chassis and interfitting with the resilient member.

3. In combination, a supporting structure having a plurality of openingstherein, a radio chassis having a movable control member, means arrangedto support the chassi with limited freedom of movement in all directionsincluding a resilient rotatable member mounted in each of said openingsand carried by said supporting structure, a drive connection from one ofsaid rotatable members to said control member arranged to adjust thecontrol member to any one of a plurality of positions, and a driveconnection from another of'said rotatable members to said cont ol memberarranged to adjust the consupporting trol member through a limited rangeof continuou movement from the position to which it has been adjusted bysaid one rotatable member, said drive connections including a shaftsupported on the chassis and interfitting with the resilient member.

4. In combination, a vertical panel having an opening therein, a radiochassis disposed behind the panel and having a movable control member;means arranged to support the chassis with limited freedom of movementin all directions, said supporting means comprising a drive memberformed of flexible material and disposed in the panel opening; a driveconnection between said drive member and said movable control member,and a control knob disposed in front of the panel and connected toactuate said drive member through a desired range of movement, saiddrive connection including a shaft supported On the chassis andinterfitting with the resilient member.

5. In combination, a vertical panel having at least two openingstherein, a radio chassi disposed behind the panel and having a movablecontrol member; resilient means arranged to support the chassis withlimited freedom of movement in all directions, said supporting meanscomprising drive members formed of flexible material and disposed insaid panel open ings, a drive connection between one of said driveconnected to actuate said drive members.

6. A radio device as claimed in claim 5 in which the movable controlmember is supported on the chassis for longitudinal movement and thedrive members are supported for rotation in the panel openings.

7. In combination, a radio chassis having a movable control member, arotatable supporting member formed of resilient material and arranged tosupport at least a portion of the weight of the chassis, a drive shaftconnected to the said control member and arranged coaxially with thesupporting member, means connecting the supporting member and driveshaft arranged not only to transmit torque to the drive shaft but topermit limited endwise movement of the drive shaft in the supportingmember, and a control knob adapted to rotate the said supporting member.

SIDNEY Y. WHITE.

